Deuterium-enriched risperidone

ABSTRACT

The present application describes deuterium-enriched risperidone, pharmaceutically acceptable salt forms thereof, and methods of treating using the same.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority benefit under 35 U.S.C. §119(e)of U.S. Provisional Patent Application Ser. No. 60/972,789 filed 15 Sep.2007. The disclosure of this application is incorporated herein byreference.

FIELD OF THE INVENTION

This invention relates generally to deuterium-enriched risperidone,pharmaceutical compositions containing the same, and methods of usingthe same.

BACKGROUND OF THE INVENTION

Risperidone, shown below, is a well known atypical antipsychoticmedication.

Since risperidone is a known and useful pharmaceutical, it is desirableto discover novel derivatives thereof. Risperidone is described in U.S.Pat. Nos. 4,804,663, 5,453,425, and 5,616,587; the contents of which areincorporated herein by reference.

SUMMARY OF THE INVENTION

Accordingly, one object of the present invention is to providedeuterium-enriched risperidone or a pharmaceutically acceptable saltthereof.

It is another object of the present invention to provide pharmaceuticalcompositions comprising a pharmaceutically acceptable carrier and atherapeutically effective amount of at least one of thedeuterium-enriched compounds of the present invention or apharmaceutically acceptable salt thereof.

It is another object of the present invention to provide a method fortreating schizophrenia, comprising administering to a host in need ofsuch treatment a therapeutically effective amount of at least one of thedeuterium-enriched compounds of the present invention or apharmaceutically acceptable salt thereof.

It is another object of the present invention to provide a noveldeuterium-enriched risperidone or a pharmaceutically acceptable saltthereof for use in therapy.

It is another object of the present invention to provide the use of anovel deuterium-enriched risperidone or a pharmaceutically acceptablesalt thereof for the manufacture of a medicament (e.g., for thetreatment of schizophrenia).

These and other objects, which will become apparent during the followingdetailed description, have been achieved by the inventor's discovery ofthe presently claimed deuterium-enriched risperidone.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Deuterium (D or ²H) is a stable, non-radioactive isotope of hydrogen andhas an atomic weight of 2.0144. Hydrogen naturally occurs as a mixtureof the isotopes ¹H (hydrogen or protium), D (²H or deuterium), and T (³Hor tritium). The natural abundance of deuterium is 0.015%. One ofordinary skill in the art recognizes that in all chemical compounds witha H atom, the H atom actually represents a mixture of H and D, withabout 0.015% being D. Thus, compounds with a level of deuterium that hasbeen enriched to be greater than its natural abundance of 0.015%, shouldbe considered unnatural and, as a result, novel over their non-enrichedcounterparts.

All percentages given for the amount of deuterium present are molepercentages.

It can be quite difficult in the laboratory to achieve 100% deuterationat any one site of a lab scale amount of compound (e.g., milligram orgreater). When 100% deuteration is recited or a deuterium atom isspecifically shown in a structure, it is assumed that a small percentageof hydrogen may still be present. Deuterium-enriched can be achieved byeither exchanging protons with deuterium or by synthesizing the moleculewith enriched starting materials.

The present invention provides deuterium-enriched risperidone or apharmaceutically acceptable salt thereof. There are twenty-sevenhydrogen atoms in the risperidone portion of risperidone as show byvariables R₁-R₂₇ in formula I below.

The hydrogens present on risperidone have different capacities forexchange with deuterium. The hydrogen atoms of risperidone are noteasily exchangeable for deuterium atoms. However, deuterium atoms at thepositions indicated by R groups may be incorporated by the use ofdeuterated starting materials or intermediates during the constructionof risperidone.

The present invention is based on increasing the amount of deuteriumpresent in risperidone above its natural abundance. This increasing iscalled enrichment or deuterium-enrichment. If not specifically noted,the percentage of enrichment refers to the percentage of deuteriumpresent in the compound, mixture of compounds, or composition. Examplesof the amount of enrichment include from about 0.5, 1, 2, 3, 4, 5, 6, 7,8, 9, 10, 12, 16, 21, 25, 29, 33, 37, 42, 46, 50, 54, 58, 63, 67, 71,75, 79, 84, 88, 92, 96, to about 100 mol %. Since there are 27 hydrogensin risperidone, replacement of a single hydrogen atom with deuteriumwould result in a molecule with about 4% deuterium enrichment. In orderto achieve enrichment less than about 4%, but above the naturalabundance, only partial deuteration of one site is required. Thus, lessthan about 4% enrichment would still refer to deuterium-enrichedrisperidone.

With the natural abundance of deuterium being 0.015%, one would expectthat for approximately every 6,667 molecules of risperidone(1/0.00015=6,667), there is one naturally occurring molecule with onedeuterium present. Since risperidone has 27 positions, one would roughlyexpect that for approximately every 180,009 molecules of risperidone(27×6,667), all 27 different, naturally occurring, mono-deuteratedrisperidones would be present. This approximation is a rough estimate asit doesn't take into account the different exchange rates of thehydrogen atoms on risperidone. For naturally occurring molecules withmore than one deuterium, the numbers become vastly larger. In view ofthis natural abundance, the present invention, in an embodiment, relatesto an amount of an deuterium enriched compound, whereby the enrichmentrecited will be more than naturally occurring deuterated molecules.

In view of the natural abundance of deuterium-enriched risperidone, thepresent invention also relates to isolated or purifieddeuterium-enriched risperidone. The isolated or purifieddeuterium-enriched risperidone is a group of molecules whose deuteriumlevels are above the naturally occurring levels (e.g., 4%). The isolatedor purified deuterium-enriched risperidone can be obtained by techniquesknown to those of skill in the art (e.g., see the syntheses describedbelow).

The present invention also relates to compositions comprisingdeuterium-enriched risperidone. The compositions require the presence ofdeuterium-enriched risperidone which is greater than its naturalabundance. For example, the compositions of the present invention cancomprise (a) a μg of a deuterium-enriched risperidone; (b) a mg of adeuterium-enriched risperidone; and, (c) a gram of a deuterium-enrichedrisperidone.

In an embodiment, the present invention provides an amount of a noveldeuterium-enriched risperidone.

Examples of amounts include, but are not limited to (a) at least 0.01,0.02, 0.03, 0.04, 0.05, 0.1, 0.2, 0.3, 0.4, 0.5, to 1 mole, (b) at least0.1 moles, and (c) at least 1 mole of the compound. The present amountsalso cover lab-scale (e.g., gram scale), kilo-lab scale (e.g., kilogramscale), and industrial or commercial scale (e.g., multi-kilogram orabove scale) quantities as these will be more useful in the actualmanufacture of a pharmaceutical. Industrial/commercial scale refers tothe amount of product that would be produced in a batch that wasdesigned for clinical testing, formulation, sale/distribution to thepublic, etc.

In another embodiment, the present invention provides a novel, deuteriumenriched compound of formula I or a pharmaceutically acceptable saltthereof.

wherein R₁-R₂₇ are independently selected from H and D; and theabundance of deuterium in R₁-R₂₇ is at least 4%. The abundance can alsobe (a) at least 7%, (b) at least 15%, (c) at least 22%, (d) at least30%, (e) at least 37%, (f) at least 44%, (g) at least 52%, (h) at least59%, (i) at least 67%, (j) at least 74%, (k) at least 81%, (l) at least89%, (m) at least 96%, and (n) 100%.

In another embodiment, the present invention provides a novel, deuteriumenriched compound of formula I or a pharmaceutically acceptable saltthereof, wherein the abundance of deuterium in R₁-R₈ is at least 13%.The abundance can also be (a) at least 25%, (b) at least 38%, (c) atleast 50%, (d) at least 63%, (e) at least 75%, (f) at least 88%, and (g)100%.

In another embodiment, the present invention provides a novel, deuteriumenriched compound of formula I or a pharmaceutically acceptable saltthereof, wherein the abundance of deuterium in R₉-R₁₁ is at least 33%.The abundance can also be (a) at least 67%, and (b) 100%.

In another embodiment, the present invention provides a novel, deuteriumenriched compound of formula I or a pharmaceutically acceptable saltthereof, wherein the abundance of deuterium in R₁₂-R₁₅ is at least 25%.The abundance can also be (a) at least 50%, (b) at least 75%, and (c)100%.

In another embodiment, the present invention provides a novel, deuteriumenriched compound of formula I or a pharmaceutically acceptable saltthereof, wherein the abundance of deuterium in R₁₆-R₂₄ is at least 11%.The abundance can also be (a) at least 22%, (b) at least 33%, (c) atleast 44%, (d) at least 56%, (e) at least 67%, (f) at least 78%, (g) atleast 89%, and (h) 100%.

In another embodiment, the present invention provides a novel, deuteriumenriched compound of formula I or a pharmaceutically acceptable saltthereof, wherein the abundance of deuterium in R₂₅-R₂₇ is at least 33%.The abundance can also be (a) at least 67%, and (b) 100%.

In another embodiment, the present invention provides an isolated novel,deuterium enriched compound of formula I or a pharmaceuticallyacceptable salt thereof.

wherein R₁-R₂₇ are independently selected from H and D; and theabundance of deuterium in R₁-R₂₇ is at least 4%. The abundance can alsobe (a) at least 7%, (b) at least 15%, (c) at least 22%, (d) at least30%, (e) at least 37%, (f) at least 44%, (g) at least 52%, (h) at least59%, (i) at least 67%, (j) at least 74%, (k) at least 81%, (l) at least89%, (m) at least 96%, and (n) 100%.

In another embodiment, the present invention provides an isolated novel,deuterium enriched compound of formula I or a pharmaceuticallyacceptable salt thereof, wherein the abundance of deuterium in R₁-R₈ isat least 13%. The abundance can also be (a) at least 25%, (b) at least38%, (c) at least 50%, (d) at least 63%, (e) at least 75%, (f) at least88%, and (g) 100%.

In another embodiment, the present invention provides an isolated novel,deuterium enriched compound of formula I or a pharmaceuticallyacceptable salt thereof, wherein the abundance of deuterium in R₉-R₁₁ isat least 33%. The abundance can also be (a) at least 67%, and (b) 100%.

In another embodiment, the present invention provides an isolated novel,deuterium enriched compound of formula I or a pharmaceuticallyacceptable salt thereof, wherein the abundance of deuterium in R₁₂-R₁₅is at least 25%. The abundance can also be (a) at least 50%, (b) atleast 75%, and (c) 100%.

In another embodiment, the present invention provides an isolated novel,deuterium enriched compound of formula I or a pharmaceuticallyacceptable salt thereof, wherein the abundance of deuterium in R₁₆-R₂₄is at least 11%. The abundance can also be (a) at least 22%, (b) atleast 33%, (c) at least 44%, (d) at least 56%, (e) at least 67%, (f) atleast 78%, (g) at least 89%, and (h) 100%.

In another embodiment, the present invention provides an isolated novel,deuterium enriched compound of formula I or a pharmaceuticallyacceptable salt thereof, wherein the abundance of deuterium in R₂₅-R₂₇is at least 33%. The abundance can also be (a) at least 67%, and (b)100%.

In another embodiment, the present invention provides novel mixture ofdeuterium enriched compounds of formula I or a pharmaceuticallyacceptable salt thereof.

wherein R₁-R₂₇ are independently selected from H and D; and theabundance of deuterium in R₁-R₂₇ is at least 4%. The abundance can alsobe (a) at least 7%, (b) at least 15%, (c) at least 22%, (d) at least30%, (e) at least 37%, (f) at least 44%, (g) at least 52%, (h) at least59%, (i) at least 67%, (j) at least 74%, (k) at least 81%, (l) at least89%, (m) at least 96%, and (n) 100%.

In another embodiment, the present invention provides a novel mixtureof, deuterium enriched compound of formula I or a pharmaceuticallyacceptable salt thereof, wherein the abundance of deuterium in R₁-R₈ isat least 13%. The abundance can also be (a) at least 25%, (b) at least38%, (c) at least 50%, (d) at least 63%, (e) at least 75%, (f) at least88%, and (g) 100%.

In another embodiment, the present invention provides a novel mixtureof, deuterium enriched compound of formula I or a pharmaceuticallyacceptable salt thereof, wherein the abundance of deuterium in R₉-R₁₁ isat least 33%. The abundance can also be (a) at least 67%, and (b) 100%.

In another embodiment, the present invention provides a novel mixtureof, deuterium enriched compound of formula I or a pharmaceuticallyacceptable salt thereof, wherein the abundance of deuterium in R₁₂-R₁₅is at least 25%. The abundance can also be (a) at least 50%, (b) atleast 75%, and (c) 100%.

In another embodiment, the present invention provides a novel mixtureof, deuterium enriched compound of formula I or a pharmaceuticallyacceptable salt thereof, wherein the abundance of deuterium in R₁₆-R₂₄is at least 11%. The abundance can also be (a) at least 22%, (b) atleast 33%, (c) at least 44%, (d) at least 56%, (e) at least 67%, (f) atleast 78%, (g) at least 89%, and (h) 100%.

In another embodiment, the present invention provides a novel mixtureof, deuterium enriched compound of formula I or a pharmaceuticallyacceptable salt thereof, wherein the abundance of deuterium in R₂₅-R₂₇is at least 33%. The abundance can also be (a) at least 67%, and (b)100%.

In another embodiment, the present invention provides novelpharmaceutical compositions, comprising: a pharmaceutically acceptablecarrier and a therapeutically effective amount of a deuterium-enrichedcompound of the present invention.

In another embodiment, the present invention provides a novel method fortreating schizophrenia comprising: administering to a patient in needthereof a therapeutically effective amount of a deuterium-enrichedcompound of the present invention.

In another embodiment, the present invention provides an amount of adeuterium-enriched compound of the present invention as described abovefor use in therapy.

In another embodiment, the present invention provides the use of anamount of a deuterium-enriched compound of the present invention for themanufacture of a medicament (e.g., for the treatment of schizophrenia).

The present invention may be embodied in other specific forms withoutdeparting from the spirit or essential attributes thereof. Thisinvention encompasses all combinations of preferred aspects of theinvention noted herein. It is understood that any and all embodiments ofthe present invention may be taken in conjunction with any otherembodiment or embodiments to describe additional more preferredembodiments. It is also to be understood that each individual element ofthe preferred embodiments is intended to be taken individually as itsown independent preferred embodiment. Furthermore, any element of anembodiment is meant to be combined with any and all other elements fromany embodiment to describe an additional embodiment.

DEFINITIONS

The examples provided in the definitions present in this application arenon-inclusive unless otherwise stated. They include but are not limitedto the recited examples.

The compounds of the present invention may have asymmetric centers.Compounds of the present invention containing an asymmetricallysubstituted atom may be isolated in optically active or racemic forms.It is well known in the art how to prepare optically active forms, suchas by resolution of racemic forms or by synthesis from optically activestarting materials. All processes used to prepare compounds of thepresent invention and intermediates made therein are considered to bepart of the present invention. All tautomers of shown or describedcompounds are also considered to be part of the present invention.

“Host” preferably refers to a human. It also includes other mammalsincluding the equine, porcine, bovine, feline, and canine families.

“Treating” or “treatment” covers the treatment of a disease-state in amammal, and includes: (a) preventing the disease-state from occurring ina mammal, in particular, when such mammal is predisposed to thedisease-state but has not yet been diagnosed as having it; (b)inhibiting the disease-state, e.g., arresting it development; and/or (c)relieving the disease-state, e.g., causing regression of the diseasestate until a desired endpoint is reached. Treating also includes theamelioration of a symptom of a disease (e.g., lessen the pain ordiscomfort), wherein such amelioration may or may not be directlyaffecting the disease (e.g., cause, transmission, expression, etc.).

“Therapeutically effective amount” includes an amount of a compound ofthe present invention that is effective when administered alone or incombination to treat the desired condition or disorder. “Therapeuticallyeffective amount” includes an amount of the combination of compoundsclaimed that is effective to treat the desired condition or disorder.The combination of compounds is preferably a synergistic combination.Synergy, as described, for example, by Chou and Talalay, Adv. EnzymeRegul. 1984, 22:27-55, occurs when the effect of the compounds whenadministered in combination is greater than the additive effect of thecompounds when administered alone as a single agent. In general, asynergistic effect is most clearly demonstrated at sub-optimalconcentrations of the compounds. Synergy can be in terms of lowercytotoxicity, increased antiviral effect, or some other beneficialeffect of the combination compared with the individual components.

“Pharmaceutically acceptable salts” refer to derivatives of thedisclosed compounds wherein the parent compound is modified by makingacid or base salts thereof. Examples of pharmaceutically acceptablesalts include, but are not limited to, mineral or organic acid salts ofthe basic residues. The pharmaceutically acceptable salts include theconventional quaternary ammonium salts of the parent compound formed,for example, from non-toxic inorganic or organic acids. For example,such conventional non-toxic salts include, but are not limited to, thosederived from inorganic and organic acids selected from1,2-ethanedisulfonic, 2-acetoxybenzoic, 2-hydroxyethanesulfonic, acetic,ascorbic, benzenesulfonic, benzoic, bicarbonic, carbonic, citric,edetic, ethane disulfonic, ethane sulfonic, fumaric, glucoheptonic,gluconic, glutamic, glycolic, glycollyarsanilic, hexylresorcinic,hydrabamic, hydrobromic, hydrochloric, hydroiodide, hydroxymaleic,hydroxynaphthoic, isethionic, lactic, lactobionic, lauryl sulfonic,maleic, malic, mandelic, methanesulfonic, napsylic, nitric, oxalic,pamoic, pantothenic, phenylacetic, phosphoric, polygalacturonic,propionic, salicyclic, stearic, subacetic, succinic, sulfamic,sulfanilic, sulfuric, tannic, tartaric, and toluenesulfonic.

EXAMPLES

Table 1 provides compounds that are representative examples of thepresent invention. When one of R₁-R₂₇ is present, it is selected from Hor D. 1

2

3

4

5

6

Table 2 provides compounds that are representative examples of thepresent invention. Where H is shown, it represents naturally abundanthydrogen. 7

8

9

10

11

12

Numerous modifications and variations of the present invention arepossible in light of the above teachings. It is therefore to beunderstood that within the scope of the appended claims, the inventionmay be practiced otherwise that as specifically described herein.

1. A deuterium-enriched compound of formula I or a pharmaceuticallyacceptable salt thereof:

wherein R₁-R₂₇ are independently selected from H and D and provided thatat least one of R₉₋₁₁ and R₁₆₋₂₇ is D.
 2. A deuterium-enriched compoundof claim 1, wherein the abundance of deuterium in R₉-R₁₁ is selectedfrom at least 33%, at least 67%, and 100%.
 3. A deuterium-enrichedcompound of claim 1, wherein the abundance of deuterium in R₁₆-R₂₄ isselected from at least 11%, at least 22%, at least 33%, at least 44%, atleast 56%, at least 67%, at least 78%, and 100%.
 4. A deuterium-enrichedcompound of claim 1, wherein the abundance of deuterium in R₂₅-R₂₇ isselected from at least 33%, at least 67%, and 100%.
 5. Adeuterium-enriched compound of claim 1, wherein the compound is selectedfrom compounds 1-4 of Table 1: 1

2

3

4

or a pharmaceutical acceptable salt, wherein when one of R₁-R₂₇ ispresent, it is selected from H or D.
 6. A deuterium-enriched compound ofclaim 1, wherein the compound is selected from compounds 5-8 of Table 2:5

6

7

8

.


7. A pharmaceutical composition, comprising: a pharmaceuticallyacceptable carrier and a therapeutically effective amount of a compoundof claim 1 or a pharmaceutically acceptable salt form thereof.
 8. Amethod for treating schizophrenia comprising: administering, to apatient in need thereof, a therapeutically effective amount of acompound of claim 1 or a pharmaceutically acceptable salt form thereof.